There has been proposed a scheme in which when a thin plate is sliced from a column-shaped member by means of wire electric discharge machining, an electrode wire is wrapped around a plurality of guide rollers which are spaced apart from one another to form a multitude of spaced-apart cut wire portions, and electric power is separately supplied to the individual cut portions to cause discharges at the same time for improved productivity (for example, a first patent document).
In this case, though all the cut wire portions become conductive with respect to one another, a coil is formed between any adjacent two of the cut wire portions by winding the electrode wire around a specific guide roller in a plurality of turns, whereby the insulation performance between the individual cut wire portions is improved by the impedance of each coil arranged therebetween, thereby suppressing a voltage impressed on a specific cut wire portion from being distributed to adjacent cut wire portions.